This is Prashanth. I'm one of the newest users of the forum. I have a question to the community about Surface finish. Can anyone tell me the possible ways to increase the as-sprayed coating roughness? We want the roughness to be min 250 Ra microinch but are getting only 200. The coating is NiCrAlY sprayed using HVOF system

One factor that will influence the as sprayed surface texture is the powder product.

Making the surface texture rougher by changing spraying parameters will tend to degrade the properties of the coating. Depending on the thickness of your coating, the roughness of the grit blast preparation may influence final coating texture.

Is the rougher coating wanted for better adhesion for a top coat ie a bond/base coat? I would be inclined to look for an alternative powder product that naturally gives a slightly coarser texture (coarser or wider particle size distribution).